Compressor



Filed 001;. 5, 1957 IN V EN TORS KARL M. GERTEIS BY ROBERT W- AYLlNG ATTORNEY which may result in bearing failure. 'dition, a large lubricant charge is provided for the com- United States Patent Gfifice 3,008,628 Patented Nov. 14, 1961 3,008,628 COMPRESSOR Karl M. Gerteis and Robert W. Ayling, Syracuse, N.Y., Y assignors to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Oct. 3, 1957, Ser. No. 687,976 7 Claims. (Cl. 230-58) This invention relates to hermetic compressors and more particularly to a hermetic compressor of the type in which the crankshaft is vertically disposed and the motor drive therefor is located above the compression mechanism.

In recent years the trend has been to make small, inexpensive, high capacity compressors. This trend has been spurred by the competitive nature of the refrigeration industry and also by the need to decrease the size of the refrigeration circuits of room air conditioners and self-contained units into small envelopes which are presently more acceptable to the buying public. Included among the ways which have been utilized to achieve these objectives in refrigeration compressors are more compact cylinder arrangements and the use of higher speeds.

Specifically, these results have been achievedby the radial orientation of cylinders in the compressor and also the -.use of two-pole motors which operate at synchronous speeds of 3600 rpm. instead of the usual four-pole motors operating at 1800 r.p.m.

Unfortunately, this reduction in size of the. compressor envelope has amplified a well known problem in the refrigeration circuit operation, namely, dilution of the crankcase oil with refrigerant during machine shutdown due to the solubility of the refrigerant in the lubricant. One start-up of the compressor the oil-refrigerant mixture foams violently due to pressure reduction and agitation and the bearings will receive inadequate lubrication To oifset this conpressor to insure that a sutficient amount of lubricant is available under all conditions to lubricate the comtion purposes.

A hermetic compressor of the welded shell type commonly has its crankshaft vertically disposed with the motor located over the crankcase and the cylinders.

Under the cylinders the shell housing of the compressor functions as an oil sump.

In line with the practice to provide large oil charges for the compressor, the sumps are made unusually large by making the lower portion of the shell either of great depth or width to provide the needed oil sump volume. Both methods of providing oil sump space result in awkward shell configurations which tend to minimize the advantage of the previously mentioned reduction in size.

The chief object of the present invention is to provide a compressor with an oil sump having a flexible nature, so that a wide range of compressor silhouettes are available for various uses.

Another object of the invention is to provide a compressor having a two-level oil sump.

A still further object is to provide a compressor having an oil sump wherein the oil level may be above'the crankcase level without interfering with the operation of the compressor by flooding the crankcase. These and other objects will be made more apparent from the following description.

reciprocating type comprising at least one cylinder, a piston within said cylinder, a crankcase, a motor compartment, a crankshaft vertically extending in said crankcase and said motor compartment, and a motor connected to the end of the crankshaft. The crankshaft is operatively connected to the piston. A partition separates the crankcase from the motor compartment. The lower portion of the compressor defines an oil sump in communication with the crankcase, said oil sump also being in communication with the motor compartment which is maintained at substantially suction gas pressure. During operation of the compressor bypass gases from the cylinder pass around the piston, increasing the pressure within the crankcase substantially. The difference of pressures acting on the surfaces of the lubricant in the sump creates two sump levels and substantially .displaces the lubricant in the crankcase.

The attached drawing illustrates a preferred embodiment of the invention, in which:

FIGURE 1 is a view partly diagrammatic and partly in section of a refrigeration circuit having a hermetic compressor employing the present invention.

Referring to FIGURE 1, there is shown the refrigeration circuit having a compressor embodying the present invention. The refrigeration circuit itself comprises the compressor 2 which is connected to the discharge line which is in turn connected to the condenser 91, the liquid line 92, expansion means 93, the evaporator 94 and the suction line 95. These units are connected in a circuit 7 in which the hot gaseous refrigerant from the compressor 2 is condensed within the condenser 91, passed through the liquid line 92 to the expansion means 93 and then into the evaporator 94. The liquid refrigerant in the evaporator is evaporated by a heat exchange process with the medium being cooled, the gaseous refrigerant being returned through the suction line to the compressor 2. Located on the suction line 95 is a suitable bulb 96 which reflects the temperature of refrigerant in line 95 and which is connected by line 97 to the expansion means 93 which meters the amount of liquid refrigerant passed to the evaporator 94.

The compressor 2 comprises an upper shell 4 and a.

lower. shell 5. These shells are provided with flange sections 6 and 7 which are intended to meet in sealing contact. Also included in the compressor is a third shell 8 having a flange 9 which is joined tov the flanges 6 and 7, as illustrated by the annular weld 10. By this construction a hermetic housing is formed.

The shell 8 has provided therein suitable openings 11 in the flange 9. The shell 8 also has a lower opening 12. Mounted within the inner shell -8 is a compressor block 15 which consists of a motor portion 16 and a crankcase portion 17 divided by a suitable partition 18. The crankcase flange portion encompasses the crankcase 14. Located in the crankcase portion 17 are suitable cylinders 19 and 20. It will be appreciated any desired number of cylinders may be employed. These cylinders are formed to pass through the crankcase portion 17. Suitable pistons 21 and 22 are reciprocatingly mounted Within the cylinders 19 and 20 and these pistons have mounted therein suitable wrist-pins 23 and 24, which are in turn rotatably connected to the connecting rods 25 and 2.6. These connecting rods 25 and 26 are rotatably connected to the eccentric portion of the crank-- shaft 30.

At the extremities of the cylinders 19 and 20 are located suitable valve assemblies 31 and 32 which may be similar to those shown in the co-pending application in the name of Karl M. Gerteis, Serial No. 687,975, filed October 3, 1957, now Patent No. 2,935,248, granted May 3, 1960. These valve assemblies are retained within their respective positions by suitable spring retainers 3 33 and 34. These spring retainers 33 and 34 are biased between the valve plate assemblies 31 and 32 and the shell 8, thereby maintaining the valve assemblies in position.

On the compressor block, two circular sealing flanges 37 and 38 are provided in concentric spaced relationship. These particular flanges are provided with suitable rings 39 and 40, which seal the space between the block and the shell 8, thereby defining an annular space 41 into which the gas compressed within the cylinders 19 and 20 is discharged. This construction is more fully described in the co-pending application in the name of Karl M. Gerteis, Serial No. 687,977, filed October 3, 1957. Discharged gases are passed from the compressor through the discharge passage 42 which is a short connecting tube extending through the shell 8 and the shell and connected to the hot gas line 90. If it is desired, suitable cavities may be incorporated in the annular space 41 to aid in muffling the discharge gases which are passed from the various cylinders of the compressor. In order to introduce these gases into the various cylinders, suction gas returning through line 95 is introduced through the opening 63 in the shell 4. This opening 63 permits suction gas to pass through the motor compartment and through the various suction ports 45 at the junction of the partition 18 and the motor block 15. The suction ports are connected to annular spaces 45' located beneath the valve assemblies 31 and 32;

It will be noted at this point that the various suction openings 45 are the only openings located in the vicinity of partition 18-with the exception of the bearing 46 through which the crankshaft 30 is journalled. This crankshaft 30 comprises a straight portion 50 which is adapted to be connected to the motor 56, a bearing portion 51, which is adapted to be journalled within the bearing 46, an eccentric portion 52 adapted to be connected to the various connecting rods which are operatively associated with the pistons, a counterweight member 53 which is connected to the shaft to aid in counteracting the unbalance of the eccentric portion 52 and a lower bearing portion 54 which is journalled within the bearing block 64.

The motor 56 comprises a stator 57 which is mounted within the motor flange portion 16 of the compressor block. The stator is inductively connected to the rotor 58 which is force-fitted onto the crankshaft section 50'. Located and attached to the rotor 58 is a suitable counterweight 59 which is also adapted to aid in counteracting the unbalance of the eccentric portion of the crankshaft.

In order to pass electric current from a suitable source to the stator 57, a suitable plug 60 is hermetically sealed through the wall of the shell 4 and is connected to suitable conductors 61 which are connected to the stator 57.

The crankshaft 30 is journalled Within the lower bearing block 64 which has mounted therein the bearing insert 65. This bearing block 64 is maintained in position by a suitable snap ring 62 which seats within an annular groove in the compressor block 15. This bearing block further includes a thrust bearing 66 which has a central opening 67. This opening 67 is in communication with the eye of a pump 68 which is a vertically extending concentric opening in the lower portion of the crankshaft. The eye of the pump is connected to the radial hole 69 which extends outwardly and is in communication with the annular space 71. This annular space 71 is in communication with the bypass filter 73 by means of the passage 72.

Located in the crankshaft is an eccentric vertical passage 76 which is in communication with the radim hole 69 and this vertical passage is in communication with the lower bearing insert 65, the eccentric bearings and the upper bearing 46.

Considering the operation of the compressor, suction gas passes from the suction line 95 into the opening 63 and the gas passes over the motor 56, suitably cooling the motor and then passes into the suction inlets 45.

The suction gas passes to the annular space beneath the valve assemblies 31 and 32 and then into the cylinders 19 and 26 through the suction valves of the assemblies. On the compression stroke the gases are passed through the valve plate into the annular space 41. All the cylinders of the compressor discharge their gases into this annular space 41 and if desired, as previously mentioned, suitable mufiiing chambers may be provided to remove the pulsating nature of the gases discharged into the passage. These gases then pass through the tube 42 into the discharge line 90 and follow the previously outlined circuit of the refrigeration system.

With respect to the lubrication system of the unit, oil is stored in the sump 76 of the compressor, which is the lower portion of the shell 5. The bearing block 64 is provided with suitable openings 12 which place the sump 76 in communication with the crankcase 14. Simultaneously, the sump section is in communication with the annular space which lies between the shells 5 and 8 and this space 80 is in communication with the motor compartment by means of the openings 11 in the flange 9 of the shell 8. Initially, the oil and refrigerant mixture lies at the bottom of the shell 5, a portion being in the sump 76, another portion within the crankcase 14 and also possibly another portion within the annular space 80. Upon start up, the shaft 30 rotates and since the bearing block 64 is substantially submerged in oil, oil will pass upwardly through the opening 67 in the thrust bearing 66. This oil enters the eye of the lubricant pump of the compressor which comprises the previously mentioned plurality of openings. The oil passes through the vertical passage 68 and is urged outwardly by centrifugal forces through the radial passages 69, a portion of the oil passing into the annular space 71 through the passage 72 and into the filter 73 where the oil is then discharged into the crankcase 14. The remainder of the oil which is cast outwardly through the radial opening 69 is forced through the vertical passage 70 to the various bearing surfaces of the compressor.

The present invention utilizes the annular space 80 which encompasses the compression section of the compressor as an oil storage space. This annular space is utilized in the following fashion.

As previously mentioned, the motor compartment 13 and the crankcase 14 are separated by the partition 18. During normal operation of the compressor during the compression stroke, as a result of the imperfection of the sealing means utilized between the pistons and the cylinders, a substantial amount of bypass gases at discharge gas pressure enters into the crankcase 14. After an interval of operation, this pressure will increase to a value between discharge and suction pressure. 'It is apparent that the lubricant located within the crankcase has acting on the surface thereof a pressure greater than the pressure on the lubricant located in the annular space 80 which is suction gas pressure. Since the respective pressures are unequal, a difference in lubricant head between the first and second oil levels will occur in order to equalize this difference in pressure. It therefore follows that most of the oil within the crankcase 14 will be displaced therefrom and be maintained at a level as shown as 77 in FIGURE 1. In actual practice the lubricant on the crankcase is fully displaced and gas from the crankcase is bubbled through the lubricant to the motor compartment. With respect to the oil level within the annul7a8r space 80, this level will be approximately as shown as With this construction it is immediately apparent that one of the oil levels of the compressor may reach a point well above the level of the various pistons and cylinders of the compressor. However, this is possible without interfering with the pumping action of the compressor since the crankcase, which under normal conditions is flooded, is not because of the diiferencein pressure which permits the oil within the crankcase to be displaced therefrom. The present invention permits the ,5. use ofacompressor shell configurations which are not normally available. The present invention gives great versatility to compressors because of the great variety of :shapes which may be used to .dictated by the particular environment in which the compressor is used. In some situations, it will be also noted that the motor cavity may be also utilized for the storage of lubricant since it is should pass from the evaporator through the suction line 95 into the compressor shell, this liquid refrigerant would immedately fall into the sump of the compressor through the openings '11 in the flange 9 of the shell 8 where the heatof the compression mechanism would evaporate .the refrigerant.

While wehave described -a preferred embodiment of our invention, it will be understood that the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

We claim:

1. In a reciprocating compressor, the combination of a housing, means defining a crankcase mounted in said housing, means defining a cylinder extending into said crankcase, a piston located in said cylinder, a vertically extending crankshaft in said crankcase operatively connected to said piston, the lower portion of said housing defining a lubricant sump, the upper portion of the housing defining a motor chamber, a motor located in said motor chamber, said motor being operatively connected to said crankshaft, a supply of the lubricant in said sump, means for passing suction gas into said motor chamber and means for placing the motor chamber in communication with the surface of the lubricant in the sump so as to provide substantially suction gas pressure upon the surface of the lubricant, the lower par-t of said crankcase being below the surface of the lubricant, said crankcase having at least one opening therein adjacent the lower end thereof below the surface of the lubricant, said crankcase being substantially closed to the interior of the housing above the surface of the lubricant, said piston fitting sufficiently loosely in said cylinder so that during operation of the compressor some discharge gas from the cylinder bypasses the piston increasing the pressure within the crankcase to substantially displace lubricant therefrom.

2. A reciprocating compressor comprising at least one cylinder, a piston in said cylinder, a crankcase, a vertically disposed crankshaft extending into said crankcase, a motor connected to an end of the crankshaft, a partition separating the crankcase from the motor, a housing enclosing the motor and the crankcase, the lower portion of the housing defining an oil sump, oil partially filling the sump, said crankcase having a portion thereof below the surface of the oil and containing oil therein when the compressor is inoperative, means operatively connecting the oil sump and said crankcase below the level of oil in said sump, and means for passing suction gas into the housing, said suction gas being incommunication with the surface of the oil in the sump to place the surface of the oil under substantially suction pressure, said piston fitting sufiiciently loosely in said cylinder so that during operation of the compressor some discharge gas from the cylinder bypasses the piston increasing the pressure within the crankcase to substantially displace lubricant therefrom.

3. A reciprocating compressor comprising a shell having a motor portion, a motor located in the motor portion of the shell, 'a plurality of cylinders located below said motor, a plurality of pistons reciprocatingly mounted in said cylinders, a crankcase, a crankshaft located in 6 said crankcase connected to .said motor and operatively connected with said pistons, a partition separating the m or por io of t s ll from th c anksas an Qi p oca d in t e l we port on of th shel oi pa ti ly filling s i ump, sai an case bei p t all submerged in said oil and having atg-le ast-one opening i a vlowerportion Q th crankca eh lsw the le el of the .o n ai sump pla in sai 9 sum i munication th s id c ankcas sa d spe in vj q n r si s bstan i l y t nly commun c t ng b t e sai amp a d sa dcran as .,mean i o p s n su t g i t h mq Po t n o the sh an tme ns fo plac n t e o o pc on i mmuniwt n t the u a he o n th sumn s a tor v d b nt ll ction pressure ,upon the surface of the ,oil, said pistons fitting in said cylinders sufliciently loosely .so that on start-up of the compressor, refrigerantgas bypasses the pistons, increasing the pressurein .the crankcase, causing oil to be displaced from said crankcase into said oil sump and raising the level of oil therein.

4. A compressor according to claim 3 in which the oil sump substantially surrounds the crankcase.

5. A reciprocating compressor comprising a sealed shell, means for passing suction gas into the upper portion of the shell, a motor located in the upper portion of the shell, an oil sump located in the lower portion of the shell, oil partially filling said sump, a plurality of radially disposed cylinders located below said motor, a plurality of pistons reciprocatingly mounted in said cylinders, a crankcase located beneath said motor, said crankcase being partially submerged in the oil sump, said crankcase constructed and arranged to be substantially closed to the interior of said shell, a crankshaft located in said crankcase and extending upwardly therefrom, said crankshaft being connected to said motor and being operatively connected with said pistons, a partition separating the motor portion of the shell from the crankcase, said shell being spaced from the crankcase so as to define an annular space therebetween, means for placing the upper portion of the shell in communication with the surface of oil in the sump to provide substantially suction pressure upon the surface of the oil, said crankcase having at least one opening therein below the level of oil par-tially filling the sump, said pistons fitting suficiently loosely in said cylinders so that during shutdown of said compressor, oil enters the crankcase through the opening and upon start-up of said compressor, refrigerant gas bypasses the pistons in the cylinders substantially increasing the pressure in the crankcase to a pressure greater than suction pressure to substantially displace the oil in said crankcase and to force the same into the annular space between the shell and the crankcase.

6. In a hermetic reciprocating compressor, the com bination of a housing, an inner shell in said housing and spaced therefrom to form an annular space between the housing and the inner shell, means defining a crankcase in said inner shell, means defining a cylinder in said crankcase, a piston located in said cylinder, a crankshaft extending into said crankcase, means connecting the crankshaft and piston, the upper portion of the housing forming a motor chamber, a motor in said motor chamber above the crankcase, said motor being operatively connected to said crankshaft, the lower portion of the housing forming an oil sump, oil in the sump, said inner shell being partially submerged in the sump, said inner shell having at least one passageway therein to place the crankcase in communication with the oil sump below the surface of the oil, said crankcase being substantially closed to the interior of the housing above the surface of the oil, means for passing suction gas into the motor chamber, and means for placing the motor chamber in communication with the surface of the oil in the sump so as to provide substantially suction pressure on the surface of the oil, said piston fitting in said cylinder sufiiciently loosely so that during shutdown of the compressor, a portion of the oil is in the crankcase, and during operation of the compressor discharge gases from the cylinder bypass the piston increasing the pressure within the crankcase to displace oil therefrom into the annular space between the housing and the inner shell.

7. In a reciprocating compressor, the combination of an upper shell, a lower shell, said upper and lower shells being connected to form a sealed housing, an inner shell within and spaced from said housing so as to form an annular space between said inner shell and said lower shell, a compressor block received by said inner shell, a vertically extending crankshaft journalled in said block, a crankcase formed in said block and encompassed by said inner shell, said block defining at least one cylinder, a piston reciprocatingly mounted in said cylinder, said piston being operatively connected to said crankshaft, a motor located in the upper shell and operativcly connected to said crankshaft, oil partially filling the lower shell, said inner shell being partially submerged in the oil, said block having at least one opening therein below the level of oil in the lower shell to place the crankcase in communication with the oil in the lower shell, said crankcase being substantially closed to the interior of the housing above the surface of the oil in the sump, said piston fitting in said cylinder sufiiciently loosely so that during operation of the compressor some discharge gases from the cylinder bypass the piston increasing the pressure Within the crankcase to displace oil therefrom into the annular space between the inner shell and lower shell.

References Cited in the file of this patent UNITED STATES PATENTS 2,199,486 Doeg May 7, 1940 2,357,522 Kelley Sept. 5, 1944 2,743,627 Christenson May 1, 1956 2,855,139 Wiebel Oct. 7, 1958 FOREIGN PATENTS 65,377 Denmark Jan. 20, 1947 568,991 Great Britain Apr. 30, 1945 UNITED STATES PATENT OFFICE CERTIFICATE- OF CORRECTION Patent No 3,008, 28 I November 14 1961 Karl M. Gerteis et al., I

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read a5 corrected below.

Column l' lir le 34, for "One" read On line 58 for "advantage" read advantages column 5 line 4 for "to" read as Signed and sealed this 17th day of April 1962,.

(SEAL) Atteat:

ESTON G. JOHNSON i DAVID L. LADD Attestihg Officer Commissioner of Patents 

